The present invention is generally in the field of liquid atomizers and in particular it is concerned with atomizers for agricultural and domestic use.
The term xe2x80x9catomizerxe2x80x9d as used herein in the specification and claims refers collectively to a device capable of emitting a fine mist of liquid. Such devices are often referred to in the art also as foggers, sprayers, mist devices, humidifiers, etc.
Atomizers used in agriculture and for domestic purposes serve for conditioning the environment both by increasing humidity such as in greenhouses and tropical gardens, for irrigation and for cooling. A variety of atomizers are known, referred to as rotary-cup atomizers, air blast/air assist etc. The present invention is concerned with pressure atomizers.
Cooling by atomized liquid is obtained by forcing a liquid, typically water, through specially designed nozzles so as to obtain a fog of ultra fine water droplets. The liquid droplets absorb heat energy of the environment and evaporate, whereby the energy (heat) consumed for converting the liquid into gas (vapor) is extracted from the environment, thus cooling the air.
The amount of moisture in the air divided by the maximum amount of moisture there could be absorbed at the same temperature (relative humidity) is a significant parameter in determining cooling potential. The lower the relative humidity, the more liquid can be vaporized, thus the more heat can be removed from the environment. Evaporative cooling can be used in most geographical zones owing to the fact that when temperature reaches its peak during day, relative humidity is normally at its lowest. For this reason, evaporative cooling is commonly used in many zones over the world.
Liquid atomizers are at times, used also as frost protectors by creating a mist layer above the agricultural growth, thus preventing frost from damaging the crops
Pressure atomizers are commonly in use and typically comprise a housing fitted with at least one outlet nozzle, a core member associated with each nozzle for generating a vortex (often referred to in the art as xe2x80x9cswirlxe2x80x9d)and a strainer/washer member packed together by screw coupling of the nozzle to the housing. The atomized spray is obtained by guiding a liquid jet through a path causing the jet to swirl and upon exiting through a fine outlet nozzle, an atomized spray is emitted.
Typically, each outlet nozzle is associated with a single housing and where covering a large area with mist is required, thus several such housing may be mounted on a splitting element, each such outlet nozzle being directed to a different direction and said splitting element being connected in turn to a liquid supply line.
It is an object of the present invention to provide a novel and improved liquid atomizer. The number of components, by one of its preferred embodiments, being reduced as compared with prior art such devices.
The present invention provides a liquid atomizer for use in agriculture and for domestic us and is aimed, by one of its preferred embodiments, at providing an atomizer comprising a reduced number of components. The liquid atomizer comprises a housing fitted with an inlet for connecting to a liquid supply line and a cavity being in flow communication with the inlet, said cavity having a longitudinal axis; a peripheral member formed with at least one outlet nozzle for emitting atomized liquid; and a vortex generating member formed with a vortex generating path being in flow communication with the cavity and extending opposite a respective outlet nozzle; each vortex generating path generates a liquid vortex about an axis transversally extending relative to the longitudinal axis of the housing.
According to one embodiment, wherein the peripheral member is integral with housing and where the vortex generating member is sealingly received within the cavity of the housing. According to another embodiment, the vortex generating member is integral with the housing and the peripheral member is mounted over the vortex generating member.
In accordance with another embodiment, the vortex generating member is coaxial with the housing and is sealingly received therewithin. By one embodiment it is radially fixable within the housing.
Typically one or more outlet nozzles are circular. However, they may also be or otherwise shaped nozzles so as to distribute a selected fog pattern.
By one preferred arrangement, the housing and the vortex generating member are cylindrical, wherein the vortex generating member is snapingly fixed to the housing and may be displaced into other functional positions. In accordance with a preferred design of this an arrangement, peripheral walls of the vortex generating member sealingly bear against inner walls of the housing, thus preventing liquid flow between the walls of the vortex generating member and the housing. However, a sealing member may be introduced between the vortex generating member and the housing.
In accordance with one specific and preferred embodiment, the vortex generating path generates a liquid vortex about an axis substantially perpendicular to the longitudinal axis of the housing.
In accordance with one arrangement of the invention, the vortex generating path has an inlet extending parallel to the longitudinal axis and originating at an edge of the vortex generating member. In accordance with another design, the vortex generating member has a hollow being in flow communication with the cavity and the vortex generating path has an outlet originating from the hollow. This arrangement is in particular suitable for including a sealing member between the vortex generating member and the housing.
In accordance with one arrangement, the vortex generating path has an R or P like cross-section with the center of the round portion extending opposite the respective outlet nozzle and wherein the respective leg portions of the R and P like shapes constitute the opening of the path. In accordance with a second arrangement, the vortex generating path has a cochlea-like (spiral) cross-section with the center thereof extending opposite the respective outlet nozzle.
According to a variation of the above embodiments, the vortex generating path is formed with two (or more) leg portions for increasing the flow rate, the leg portions extending from an edge of the vortex generating member which is in flow communication with the cavity, or have at least one leg being in flow communication with the cavity via a hollow formed in the vortex generating member which is in flow communication with the cavity.
In accordance with another variation of the invention, the vortex generating member comprises a plurality of vortex generating paths and the housing comprises a plurality of outlet nozzles; the vortex generating paths and the outlet nozzles being distributed at different angular divisions; the vortex generating member is fixable within the housing at different radial positions, each giving rise to cooperation of different outlet nozzles with respective vortex generating paths and to sealing of other outlet nozzles. This arrangement enables to determine the number of active nozzles within a single housing, allowing to increase or decrease the number of active nozzles so as to obtain different sectorial coverage of mist.
By another design, some of tie vortex generating paths of the vortex generating member are axially offset and some of the outlet nozzles of the housing are offset in a corresponding manner, whereby axial or angular displacement of the vortex generating member with respect to the housing entails engagement of a different vortex path with a different outlet nozzle. In this way it is possible to select different fog patterns, outlet rate, etc. By a modification thereof, at least one outlet nozzle and at least one vortex generating member are axially offset.
The housing and vortex generating member are fitted with corresponding mating members for setting the vortex generating member at the different radial positions within the housing.
The arrangement of the liquid atomizer in accordance with the present invention reduces to minimum the number of components wherein each housing is fitted with a single vortex generating member whereby a single housing is required or several outlet nozzles.
By a different application of the invention, the inlet is in flow communication with a pressure threshold valve received before or after the inlet. By a preferred embodiment, the pressure threshold valve is received within the cavity of the liquid atomizer. In accordance with one such design, the pressure threshold valve comprises a closure member biased against the inlet of the housing.
In accordance with another embodiment, the pressure threshold valve is a leakage preventing device (LPD), and wherein the closure member is spring biased against the inlet of the housing and has a piston rod connecting it with a piston, said piston being displaceable along a corresponding cylinder and is in flow communication with the cavity. The LPD arrangement provides for opening of hie closure member at a predetermined pressure threshold wherein the inlet is rapidly opened into a maximal open stage. This may be obtained by a structure in which the piston is sealingly displaceable within the cylinder and wherein liquid entering the cavity applies force on the piston in a direction entailing displacement of the closure member away from the inlet.
In accordance with such an embodiment, it is desired that the cylinder is vented to the atmosphere. In accordance with a modification of the invention, the piston is displaceable against a membrane fitted at an end of the cylinder.